箭筈豌豆种质资源萌发期抗旱指标筛选及抗旱性评价

  【目的】  萌发期干旱影响绿肥作物箭筈豌豆 (Vicia sativa L.) 生产。筛选关键、敏感抗旱评价指标，开展不同箭筈豌豆萌发期抗旱性评价，为挖掘抗旱种质和开展抗旱性品种选育提供理论依据。  【方法】  选择分布于箭筈豌豆主要种植区的14份代表性箭筈豌豆种质资源为研究对象，以蒸馏水处理为试验对照，分别设置2.5%、5%、10%和15% 等4个不同PEG-6000 (高分子聚合物聚乙二醇6000) 模拟干旱胁迫处理，测定和计算发芽率、发芽势、发芽指数、种子萌发指数、胚根长、胚芽长、胚根重、胚芽重、胚根长/胚芽长值、胚根重/胚芽重值和活力指数等11项指标及其相应抗旱系数。  【结果】  4个PEG-6000浓度胁迫不同程度地降低了供试箭筈豌豆各测试指标及其抗旱系数 (P < 0.05)，14个种质资源的测试指标变异系数为11.40%～48.71%，抗旱系数的变异系数为10.20%～46.56%。大多数测试指标抗旱系数间存在显著或极显著相关关系，相关系数变化范围为0.182～0.956。基于主成分分析方法，各指标抗旱系数降维为3个相互独立的主成分综合指标，3个主成分综合指标累计贡献率为85.9%。基于模糊数学隶属函数方法，各资源抗旱性综合评价指数 (D值) 平均数为0.420，变异系数为50.6%，9号种质资源D值最高，10号种质资源D值最低。基于聚类分析方法，14份箭筈豌豆资源可根据抗旱特性不同聚为4类，抗旱等级划分与不同等级D值大小相一致，9号资源为强抗旱资源，14号资源为较强抗旱资源，中等与弱抗旱资源占总资源量85.8%。基于逐步回归方法，抗旱性综合评价指数D值与各鉴定指标抗旱系数的回归关系为D = 1.31X₁ + 0.566X₂ + 0.183X₃–1.068 (R2 = 0.991, P < 0.001, X₁、X₂、X₃分别表示发芽指数、胚根重和胚根长抗旱系数)。  【结论】  抗旱性综合评价指数D值是表征种质资源萌发期抗旱特性的有效指标，发芽指数、胚根重和胚根长抗旱系数可以解释99.1%的不同种质资源抗旱性变异，鉴定获得2份萌发期抗旱性较强箭筈豌豆资源，85%以上的供试箭筈豌豆资源为中等或弱抗旱性种质资源，选择抗旱性种质资源是箭筈豌豆高效生产的重要方面。

Screening of drought-resistance index and drought-resistance evaluation of common vetch (Vicia sativa L.) germplasms at germination stage

  【Objectives】  Common vetch ( Vicia sativa L.) growth is easily inhibited by drought at germination stage. Thus, there is need for screening of critical, sensitive drought-resistance indicators and assessing the drought-resistance capacity of common vetch germplasms for identification and breeding of drought-resistant germplasms.   【Methods】  Fourteen common vetch germplasms were collected from the dominant common vetch planting regions in China. Four different PEG-6000 concentrations (2.5%, 5%,10% and 15%) were prepared to simulate different drought stress levels, while distilled water treatment was the control. Indicators such as germination rate, germination potential, germination index, seed germination index, radicle length, embryo length, radicle weight, embryo weight, ratio of radicle length to embryo length, ratio of radicle weight to embryo weight, vigour index and their drought-resistance indexes (DRI) were measured and calculated.  【Results】  All the four stress treatments significantly decreased the values of tested indicators and drought-resistance coefficients of all tested germplasms, with CV range of 11.40%?48.71% and 10.20%?46.56% for indicators and drought-resistance coefficients, respectively. Most measured indicators showed significant correlation with r value range of 0.182 to 0.956. Based on the principal component analysis, the DRI of the measured indicators were reduced to three independent integrated indicators, of which three contributed 85.9% of the cumulative variance. According to fuzzy mathematics membership function, the average drought-resistance comprehensive evaluation index (D value) of the tested germplasms was 0.420 with CV of 50.6%, while the maximum and the minimum D values were recorded for code 9 and code 10 germplasms, respectively. The 14 tested germplasms were clustered into four drought-resistance grades, and the grade of each germplasm was in accordance with its D value. The highest drought-resistant germplasms were those with code 9 and code 14, respectively, while 85.8% of the germplasms fell into the moderate and weak drought-resistance category. Stepwise regression produced a significant relationship between D value and drought-resistance coefficients of indicators (D = 1.31X₁ + 0.566X₂ + 0.183X₃–1.068; R2 = 0.991; P< 0.001; X₁, X₂, and X₃ represent DRI for germination index, embryo weight and embryo length, respectively).  【Conclusions】  The D value is an effective index for indicating drought-resistance characteristics at germination stage. The drought-resistance coefficients of germination index, embryo weight, and embryo length explained 99.1% of drought-resistance variation of the assessed germplasms. Two common vetch germplasms with high drought-resistance were identified, while more than 85% of the tested germplasms exhibited moderate and weak drought-resistance at germination stage. Overall, this study demonstrates that drought-resistance screening and evaluation are highly important for choosing drought-resistant germplasm and efficient growth and production of common vetch.